Hey all. Lets say one had access to a nitro tap. Do you think I could try my homebrew on it and if I didn't dig it go back to straight co2? Or would putting nitro in it (for lack of a better term) contaminate the beer and have to finish it on nitro? Thank guys.

The reason nitrogen is used is because it doesn't dissolve in beer (at least it's negligible compared to CO2). So it won't stay in there. Beers served on nitro taps are carbed very low compared to those served through a traditional faucet. So as SpentGrains said, you'll have to tweak it a bit switching between the two. Excessive foaming through the stout faucet is probably a sign it's too carbonated.

Assuming you start with the nitro to try it out, carb it with straight CO2 first anyways, just to save the nitro. Except carb it to lower levels than you normally would, maybe 5-7psi (1.1-1.3vol) or so, depending on your setup. Then you can switch it over to nitro at around 30psi or so, which should keep it near the same CO2 pressure or close to it since the ratio of nitro to CO2 in blends varies a little bit. If you decide to take it off nitro, just vent the keg and the beer will still be carbed to the low level (1.3-1.5vol), and then you'd just have to bump it back up a little higher with CO2 to get to a more standard carb level. Although after you try nitro, I'm not sure you'll want to go back!